- #1
Abu
- 39
- 16
- Homework Statement
- A spring of negligible mass has force constant k = 800 N/m. You place the spring vertically with one end on the floor. You then lay a 1.6 kg block on top of the spring and release the book from rest. Find the maximum distance the spring will be compressed
- Relevant Equations
- F = kx
Hi everyone, just a quick question..
I tried this problem using Newtons laws, not conservation of energy, and I got an answer exactly half of what the correct answer is, and I'm not sure why. Here is what I did:
Net force = zero once the spring is compressed, therefore
mg - kx = 0
mg = kx
mg/k = x
1.6(9.8)/800 = x
x = 1.96 cm
The actual answer is 3.92 cm however, and I don't know why.
If I do this problem using conservation of energy, I get the correct answer but I can't explain why my Newtons laws method is wrong.
Thanks for your consideration!
I tried this problem using Newtons laws, not conservation of energy, and I got an answer exactly half of what the correct answer is, and I'm not sure why. Here is what I did:
Net force = zero once the spring is compressed, therefore
mg - kx = 0
mg = kx
mg/k = x
1.6(9.8)/800 = x
x = 1.96 cm
The actual answer is 3.92 cm however, and I don't know why.
If I do this problem using conservation of energy, I get the correct answer but I can't explain why my Newtons laws method is wrong.
Thanks for your consideration!